Downhole pulsing shock-reach extender method

ABSTRACT

A downhole pulsing-shock reach extender method for overcoming static friction resistance in coiled-tubing drilling-fluid-pressure driven downhole operations, generating pulsed hydraulic shocks at the workstring by creating a fluid-hammer condition by repeated sudden opening and closing of a set-pressure snap-acting valve, using an essentially constant or slowly changing normal drilling-fluid pressure that will not damage other components of the workstring, thereby extending the depth limit of downhole operations. A poppet and calibrated spring act as a set-pressure snap-acting valve, and a tapering constriction and constricted throat in the main flow of drilling fluid or mud builds up higher pressure to open the valve, while bypass portways allow for limited flow and equilibration around the valve. The rapid equilibration of pressure upon the opening of the valve, combined with the force of the calibrated spring, allows a rapid closing of the valve, which sets up a fluid-hammer hydraulic shock, in a repeating cycle.

BACKGROUND

This invention is a downhole pulsing-shock reach extender method for overcoming static friction resistance in coiled-tubing drilling-fluid-pressure driven downhole operations.

Drilling, in its broad sense, includes the initial drilling of a hole plus many subsequent trips down the hole for workover and inspection. Where older methods of drilling use sections of rigid pipe threaded together, coiled-tubing drilling uses a somewhat flexible, continuous tube that can be spooled when not in use. Where the power for rigid-pipe drilling is applied at the turntable on the rig, the power for coiled-tubing drilling is instead applied at or near the drill bit or workstring by converting pressure applied to drilling fluid or drilling mud at the wellhead, transmitted down the great length of coiled tubing, and converted to rotational force by a fluid motor or mud motor. This technique allows directional drilling, including horizontal drilling, and including changes of direction during drilling. In coiled-tubing operations, the depth of a hole might include substantial portions of horizontal or near-horizontal runs.

In rigid-pipe drilling, the function of drilling fluid or drilling mud is to provide lubrication, flushing of tailings, and counter pressure down the hole. Coiled-tubing drilling instead uses the drilling fluid or mud for an additional purpose of transmitting power or force to the workstring, which is underground, thousands of feet distant.

Coiled-tubing operations will always encounter increased resistance at increasing depths. Although the coiled tubing is straightened before insertion, there is a likelihood of some residual shape memory to nudge the deployed tubing away from being perfectly straight. Directional drilling usually involves changes of direction, and each change of direction provides a point of increased drag while diminishing any benefit from downward, insertion force applied at the wellhead. Because there is likely to be at least some drag all along the surface of the deployed tubing, a longer, or deeper, run will encounter increasing total drag. Therefore, very deep coiled-tubing operations encounter increased drag, or static friction, which eventually cannot be overcome. This limits the depths attainable by the operation.

It is known that a given amount of force, when applied gradually or constantly, will not be sufficient to overcome static friction, but the same total amount of force, when applied as pulses, will overcome the static friction. For example, a nail that cannot be pressed into a block of wood can be hammered into it. The pulse of force is able to work as intended for a brief time before being dispersed. But in coiled-tubing operations, any pulse of more pressure applied at the wellhead will dissipate, and will not be felt at the distant workstring. All changes of pressure at the workstring will necessarily be gradual, buffered changes. If too great an amount of mud pressure is forced down the coiled tubing, it will damage or destroy the mud motor.

The present art does not provide an effective way of generating pulses of hydraulic shock within the workstring itself, while avoiding the application of too much pressure within the long run of coiled tubing and at the workstring, and while avoiding damage to mud motors and other components of the workstring.

U.S. Publ. No. 2016/0312559 was published on Oct. 27, 2016 by inventors Ilia Gotlib et al. and assignee Sclumberger Technology Corp., and covers a “Pressure Pulse Reach Extension Technique.” The pressure pulse tool and technique allows for a reciprocating piston at a frequency independent of a flow rate of the fluid that powers the reciprocating. The architecture of the tool and techniques employed may take advantage of a Coanda or other implement to alternatingly divert fluid flow between pathways in communication with the piston in order to attain the reciprocation. Frequency of reciprocation may be between about 1 Hz and about 200 Hz, or other suitably tunable ranges. Once more, the frequency may be enhanced through periodic exposure to annular pressure. Extended reach through use of such a pressure pulse tool and technique may exceed about 2,000 feet.

U.S. Publ. No. 2016/0130938 was published on May 12, 2016 by inventor Jack J. Koll and assignee Tempress Technologies, Inc., and discloses “Seismic While Drilling System and Methods.” A bottom hole assembly is configured with a drill bit section connected to a pulse generation section. The pulse generation section includes a relatively long external housing, a particular housing length being selected for the particular drilling location. The long external housing is positioned closely adjacent to the borehole sidewalls to thereby create a high-speed flow course between the external walls of the housing and the borehole sidewalls. The long external housing includes a valve cartridge assembly and optionally a shock sub decoupler. While in operation, the valve cartridge assembly continuously cycles and uses downhole pressure to thereby generate seismic signal pulses that propagate to geophones or other similar sensors on the surface. The amount of bypass allowed through the valve assembly is selectable in combination with the long external housing length and width to achieve the desired pulse characteristics. The bottom hole assembly optionally includes an acoustic baffle to attenuate wave propagation going up the drill string.

U.S. Publ. No. 2014/0048283, published by Brian Mohon et al. on Feb. 20, 2014, covers a “Pressure Pulse Well Tool.” The disclosure of the Mohen publication is directed to a pressure pulse well tool, which may include an upper valve assembly configured to move between a start position and a stop position in a housing. The pressure pulse well tool may also include an activation valve subassembly disposed within the upper valve assembly. The activation valve subassembly may be configured to restrict a fluid flow through the upper valve assembly and increase a fluid pressure across the upper valve assembly. The pressure pulse well tool may further include a lower valve assembly disposed inside the housing and configured to receive the fluid flow from the upper valve assembly. The lower valve assembly may be configured to separate from the upper valve assembly after the upper valve assembly reaches the stop position, causing the fluid flow to pass through the lower valve assembly and to decrease the fluid pressure across the upper valve assembly.

U.S. Pat. No. 8,082,941 issued Dec. 27, 2011 to Alessandro O. Caccialupi et al. for a “Reverse Action Flow Activated Shut-Off Valve.” The Caccialupi flow-activated valve includes an outer body and a piston disposed in an inner cavity of the outer body. The flow-activated valve also includes one or more fluid passage exits in the outer body and one or more piston fluid passages in the piston. The one or more fluid passage exits and the one or more piston fluid passages allow fluid flow out of the valve. The flow-activated valve also includes a flow restriction member disposed in a piston inner cavity. In addition, the flow-activated valve includes a shear member disposed in the outer body, and a bias member disposed in an inner cavity of the outer body. The flow-activated valve further includes a position control member disposed in the piston and a sealing member.

U.S. Pat. No. 7,343,982 issued to Phil Mock et al. on Mar. 18, 2008 for a “Tractor with Improved Valve System.” The system covers a hydraulically powered tractor adapted for advancement through a borehole, and includes an elongated body, aft and forward gripper assemblies, and a valve control assembly housed within the elongated body. The aft and forward gripper assemblies are adapted for selective engagement with the inner surface of the borehole. The valve control assembly includes a gripper control valve for directing pressurized fluid to the aft and forward gripper assemblies. The valve control assembly also includes a propulsion control valve for directing fluid to an aft or forward power chamber for advancing the body relative to the actuated gripper assembly. Aft and forward mechanically actuated valves may be provided for controlling the position of the gripper control valve by detective and signaling when the body has completed an advancement stroke relative to an actuated gripper assembly. Aft and forward sequence valves may be provided for controlling the propulsion control valve by detecting when the gripper assemblies become fully actuated. A pressure relief valve is preferably provided along an input supply line for liming the pressure of the fluid entering the valve control assembly.

U.S. Pat. No. 2,576,923, issued on Dec. 4, 1951 to Clarence J. Coberly for a “Fluid Operated Pump with Shock Absorber,” relates in general to equipment for pumping fluid from wells and, more particularly, to an apparatus which includes a reciprocating pump of the fluid-operated type. A primary object of the invention is to provide an apparatus having cushioning means associated therewith for absorbing any fluid pressure variations which may impose hydraulic shock loads on the system. The fluid operated pumping unit includes a combination of (1) a source of a first fluid at a substantially constant pressure level; (2) a receiver for a second fluid to be pumped; (3) a pump adapted to be operating by the first fluid to pump the second fluid; (4) a shock absorber connected to the pump and having movable fluid separating means within it; (5) means for a first passage communicating between the source and the shock absorber for admitting the first fluid into the shock absorber on one side of the fluid separating means; (6) and a second passage means communicating between the receiver and the shock absorber for admitting the second fluid into the shock absorber on the opposite side of the fluid separating means.

U.S. Pat. No. 8,967,268, issued to Larry J. Urban et al. on Mar. 3, 2015, covers “Setting Subterranean Tools with Flow Generated Shock Wave.” In the Urban patent, a circulation sub is provided that has a ball seat and a circulation port that is closed when a ball is landed on the seat. An axial passage directs the pressure surge created with the landing of the ball on the seat to the port with the actuation piston for the tool. The surge in pressure operations the actuation piston to set the tool, which is preferably a packer. Raising the circulation rate through a constriction in a circulation sub breaks a shear device and allows the restriction to shift to cover a circulation port. The pressure surge that ensues continues through the restriction to the actuating piston for the tool to set the tool. The Urban patent was assigned to Baker Hughes Inc. on Nov. 30, 2011.

U.S. Pat. No. 8,939,217, issued Jan. 27, 2015 to inventor Jack J. Koll and assignee Tempress Technologies, Inc., covers a “Hydraulic Pulse Valve with Improved Pulse Control,” pictured at right. Hydraulic pulses are produced each time that a pulse valve interrupts the flow of a pressurized fluid through a conduit. The pulse valve includes an elongated housing having an inlet configured to couple the conduit to receive the pressurized fluid, and an outlet configured to couple to one or more tools. In the housing, a valve assembly includes a poppet reciprocating between open and closed positions, and a poppet seat, in which the poppet closes to at least partially block the flow of pressurized fluid through the valve. A pilot within the poppet moves between disparate positions to modify fluid paths within the valve. When the valve is open, a relatively lower pressure is produced by a Venturi effect as the fluid flows through a throat in the poppet seat, to provide a differential pressure used to move the pilot and poppet. An optional bypass reduces the pulse amplitude.

SUMMARY OF THE INVENTION

This invention provides a downhole pulsing-shock reach method for overcoming static friction resistance in coiled-tubing drilling-fluid-pressure driven downhole operations, generating pulsed hydraulic shocks at the workstring by creating a fluid-hammer condition by repeated sudden opening and closing of a set-pressure snap-acting valve, using an essentially constant or slowly changing normal drilling-fluid pressure that will not damage other components of the workstring, thereby extending the depth limit of downhole operations. A poppet and calibrated spring act as a set-pressure snap-acting valve, and a tapering constriction and constricted throat in the main flow of drilling fluid or mud builds up higher pressure to open the valve, while bypass portways allow for limited flow and equilibration around the valve. The rapid equilibration of pressure upon the opening of the valve, combined with the force of the calibrated spring, allows a rapid closing of the valve, which sets up a fluid-hammer hydraulic shock, in a repeating cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the drawings, wherein like parts are designated by like numerals, and wherein:

FIG. 1 is a schematic view illustrating the downhole pulsing-shock reach extender of the invention in use;

FIG. 2 is a sectional view of the downhole pulsing-shock reach extender of the invention with the poppet sealing the constricted throat;

FIG. 3 is a sectional view of the downhole pulsing-shock reach extender of the invention with the poppet not sealing the constricted throat;

FIG. 4 is a sectional perspective detail view of a portion of the downhole pulsing-shock reach extender of the invention;

FIG. 5 is a sectional schematic view illustrating the relative pressures within the downhole pulsing-shock reach extender of the invention with the poppet sealing the constricted throat; and

FIG. 6 is a sectional schematic view illustrating the relative pressures within the downhole pulsing-shock reach extender of the invention with the poppet sealing the constricted throat.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the downhole pulsing-shock reach extender 10 of the invention is shown schematically, in use in coiled-tubing, directional drilling, downhole operations, specifically in the removal of a previously-placed cement plug.

The downhole pulsing-shock reach extender 10 assists significantly in overcoming the static friction encountered in deep downhole coiled-tubing operations by generating pulsed hydraulic shocks by creating a fluid-hammer condition by repeated sudden opening and closing of a set-pressure snap-acting valve, using an essentially constant or slowly changing normal drilling-fluid pressure that will not damage other components of the workstring, thereby extending the depth limit of downhole operations.

In order to overcome static friction in coiled-tubing directional drilling downhole operations, it is necessary to provide some pulsation of energy at the workstring, which will take advantage of the small window of time that a force is able to work as intended before being dispersed, in a continuing cycle. No pulsation from the wellhead can effectively reach the workstring. Further, the application of an extreme amount of pressure will only damage or destroy the workstring's components. The downhole pulsing-shock reach extender 10 generates the needed pulsing shocks at the needed locus of the workstring, using the available, normal mud pressure, and without exposing the other components of the workstring to damage or destruction from excessive pressures.

The hammer or shock set up in the drilling mud inside the downhole pulsing-shock reach extender 10 will impart a jerk, also known as jolt, surge, or lurch, to the body of the extender and the other elements of the workstring, causing a mechanical or physical shock, which assists the workstring in overcoming static friction.

Referring to FIG. 2, the downhole pulsing-shock reach extender 10 comprises a tube body 1 with an outer diameter matching that of the coiled tubing itself and the other components of the workstring. In an embodiment appropriate for standard 2.375-inch tubing in a 5.5-inch casing, an outer diameter of 2.875 inches is appropriate. Inside the tube body 1 is an inflow chamber 2 that essentially matches the inside diameter of the coiled tubing. The inflow chamber therefore receives a flow of drilling fluid or mud at essentially the same pressure found in the adjacent portion of the coiled tubing. Although a major portion of the drilling mud will be channeled into a pressure-increasing configuration, a smaller portion of the mud is channeled through one or more bypass portways 3. Because this substream or these substreams are taken from the inflow chamber 2 with no concentration of the substreams, their pressure will not significantly rise, and that portion of mud will be delivered to its destination, disclosed in more detail below, substantially at equilibrium with the inflow chamber 2.

The major portion of the drilling mud is channeled into a tapering constriction 4 of the inner diameter of the tube body 1, and from the tapering constriction 4 into a constricted throat 5 having a significantly smaller inner diameter than the inflow chamber 2. In accord with Bernoulli's Principle, the resulting decrease in the speed of the fluid occurs simultaneously with an increase in pressure or potential energy.

At the beginning of the cycle at issue here, the downstream opening of the constricted throat 5 is sealed closed by a poppet 7 held against the opening by a calibrated spring 8. The poppet 7 and calibrated spring 8 are mounted in a poppet chamber 8, in such a way that the poppet 7 and calibrated spring 8 can move as necessary. Drilling mud can flow into and through the poppet chamber 6 as well. The poppet chamber 6 is the downstream continuation of the flow of mud through the downhole pulsing-shock reach extender 10. Even when the flow of mud is prevented by the face of the poppet 7 sealing the downstream opening of the constricted throat 5, there is still a small but significant flow of mud from the inflow chamber 2, through the bypass portways 3. This bypass flow ensures that other components of the workstring are never completely starved of mud, and also allows for equilibration of pressure between the inflow chamber 2 and the poppet chamber 8, which substantially negates the contribution of the overall pressure of mud in the coiled tubing, and makes the opening and closing of the set-pressure snap-acting valve formed by the poppet 7 and calibrated spring 8 dependent more precisely upon the relative pressure increase in the tapering constriction 4 and constricted throat 5 in relation to the pressure in the inflow chamber 2, and therefore the poppet chamber 6.

Still referring to FIG. 2, with the set-pressure snap-acting valve closed, the constricted throat 5 would be considered the vena contracta, or the point in the fluid stream where the diameter of the stream is the least, and fluid velocity is at its maximum, if a fluid stream existed at that time. But such a fluid stream is blocked by the face of the poppet 7, and the energy at the opening of the constricted throat exists as increased pressure or potential energy.

Referring to FIG. 3, the calibrated spring 8 is calibrated to yield at a desired pressure differential between the constricted throat 5 and the poppet chamber 6. Because there is additional surface area on the face of the poppet 7, in addition to the smaller area sealing the constricted throat 5, the initial surge of pressure will also act upon that additional surface and further snap the valve open. With that valve open, the pressurized mud from the constricted throat 5 is allowed to rush into the poppet chamber 6, equalizing the pressure. Additionally, the opening of the constricted throat 5 to the poppet chamber 6 allows the Venturi Effect to cause a reduction in fluid pressure just past the downstream opening of the constricted throat 5.

Therefore, within an extremely brief time, the downstream opening of the constricted throat 5 changes from being the locus of highest relative pressure to being the locus of lowest relative pressure. Consequently, the force of the calibrated spring 8 is sufficient to quickly close the set-pressure snap-acting valve, and the opening is abruptly shut. This abrupt shutting sets up an iteration of fluid hammer or hydraulic shock, which provides a beneficial effect to drilling or other operations underway. The cycle then repeats.

An outflow chamber 9 is provided to accept the flow of mud from the poppet chamber 6, to allow the velocity and pressure of the mud to equilibrate, settle, or buffer, and to feed the flow of mud into the rest of the workpiece and ultimately to the mud motor. The diameter of the outflow chamber 9 can be smaller than the inflow chamber 2, which will increase the velocity and pressure of the mud flow to the mud motor, and compensate for energy lost to heat and entropy in the hammering cycle. The diameter of the outflow chamber 9 can be much smaller, which will amplify the velocity and pressure of the mud flow to the mud motor above the velocity and pressure in the coiled tubing. Or the diameter of the outflow chamber 9 can be larger, which will decrease the velocity and pressure of the mud flow to the mud motor.

Referring to FIG. 4, the forces generated in the constricted throat 5 are initially focused upon just a smaller portion of the face of the poppet 7, and then when the poppet 7 begins to separate from the downstream opening of the constricted throat 5, the forces additionally act upon the rest of the face of the poppet 7, enhancing a desired snap-acting quality.

Referring to FIG. 5 & FIG. 6, in use, the flow of drilling mud under normal pressure enters the inflow chamber 2. A portion of the flow is channeled via the bypass portways 3 into the poppet chamber 6. The bulk of the mud flows into the tapering constriction 4 and the constricted throat 5. This constriction of the flow increases the pressure or potential energy of that portion of the mud flow. Initially, the face of the poppet 7 seals the downstream opening of the constricted throat 5. The calibrated spring 8 presses the poppet 7 into the sealing, closed position. The pressure difference between the constricted throat 5 and the poppet chamber 6 forces the poppet 7 open, allowing the flow of the higher-pressure mud into the poppet chamber 6, which increases the flow of mud and increases the pressure in the poppet chamber 6. Mud continues to flow through the tapering constriction 4 and constricted throat 5. With the constricted throat 5 open to the larger poppet chamber 6, the Venturi Effect causes a reduction in fluid pressure just past the opening of the constricted throat 5 into the poppet chamber 6. Pushed by the calibrated spring 8, the poppet 7 moves into the area of reduced pressure, and re-seals the downstream end of the constricted throat 5, setting up a fluid hammer or hydraulic shock, and repeating the cycle. The drilling mud then flows into the outflow chamber 9 where it is allowed to equilibrate to a velocity and pressure slightly above that of the inflow chamber 2, and out to the rest of the workstring.

An embodiment of the downhole pulsing-shock reach extender 10 is made of steel, as is known in the art. The types of drilling fluid or mud used with coiled-tubing, mud-motor operations will sufficiently cool and lubricate a unit made of steel, and will suppress any potential sparking. Other embodiments could be made from, or could have components made from, non-sparking brass or from non-corroding composite materials, if such qualities are needed.

Many other changes and modifications can be made in the system and method of the present invention without departing from the spirit thereof. I therefore pray that my rights to the present invention be limited only by the scope of the appended claims. 

I claim:
 1. A downhole pulsing-shock reach extender method for overcoming static friction resistance in coiled-tubing drilling-fluid-pressure driven downhole operations, the downhole pulsing-shock reach extender method comprising: (i) providing a pulsing-shock apparatus comprising: (a) a tube body adapted to being mounted in a coiled-tubing work string, having, in use, a wellhead end and a well-bottom end; (b) an inflow chamber at the wellhead end of said tube body, having a diameter essentially matching the inner diameter of the coiled tubing; (c) a tapering constriction at the well-bottom end of said inflow chamber; (d) a constricted throat at the well-bottom end of said tapering constriction; (e) a poppet chamber at the well-bottom end of said constricted throat; (f) a poppet movably mounted inside said poppet chamber, adapted to prevent flow from said constricted throat in a closed position and to allow flow in an open position; (g) a calibrated spring mounted inside said poppet chamber, adapted to exert a closing force against said poppet sufficient to prevent opening when pressure difference between said constricted throat and said poppet chamber is small, and to allow opening when pressure difference is large; (h) at least one bypass portway adapted to allow constant but constricted flow and pressure equilibration between said inflow chamber and said poppet chamber; and (i) an outflow chamber at the well-bottom end of said poppet chamber, adapted to convey pressurized drilling fluid to the other components of the workstring; where said poppet and said calibrated spring function as a set-pressure snap-acting valve; (ii) inserting said pulsing-shock apparatus into the workstring for a coiled-tubing downhole operation; (iii) pumping drilling fluid through the coiled tubing to the workstring; and (iv) building higher fluid pressure in said tapering constriction and constricted throat, acting upon said poppet until sufficient pressure to overcome said calibrated spring is reached, opening and allowing fluid to flow from said constricted throat, in turn allowing an increase of flow and pressure into said poppet chamber, equilibrating the pressure difference between said inflow chamber and poppet chamber, in turn allowing said calibrated spring to move said poppet back into position sealing said constricted throat, in a continuing cycle; where, in use, the continuing cycle of opening and closing the set-pressure snap-acting valve formed by said poppet and said calibrated spring sets up a fluid-hammer series of pulsing shocks which assist in overcoming the static friction forces acting to resist further entry of the drill string into the hole.
 2. The downhole pulsing-shock reach extender method of claim 1, where said tube body is made of steel.
 3. The downhole pulsing-shock reach extender method of claim 1, where said tube body has an outer diameter of 2.875 inches.
 4. The downhole pulsing-shock reach extender method of claim 1, where said tapering constriction has a taper of from 10 to 15 degrees, inclusive.
 5. The downhole pulsing-shock reach extender method of claim 1, where said constricted throat has a diameter not greater than half the diameter of said inflow chamber.
 6. The downhole pulsing-shock reach extender method of claim 1, where said constricted throat has a length greater than its diameter.
 7. The downhole pulsing-shock reach extender method of claim 1, where said poppet has a diameter double the diameter of said constricted throat.
 8. The downhole pulsing-shock reach extender method of claim 1, where said poppet and said calibrated spring are made of brass.
 9. The downhole pulsing-shock reach extender method of claim 1, where said bypass portways are arranged as openings around the diameter of said inflow chamber at the start of said tapering constriction.
 10. The downhole pulsing-shock reach extender method of claim 1, where said outflow chamber has a diameter smaller than the diameter of said inflow chamber.
 11. The downhole pulsing-shock reach extender method of claim 1, where said outflow chamber has a diameter not greater than 75% of the diameter of said inflow chamber.
 12. The downhole pulsing-shock reach extender method of claim 1, where said outflow chamber has a diameter substantially equal to the diameter of said inflow chamber.
 13. The downhole pulsing-shock reach extender method of claim 1, where said bypass portways accommodate from 10% to 33%, inclusive, of the flow in said inflow chamber.
 14. The downhole pulsing-shock reach extender method of claim 1, where said bypass portways accommodate not greater than half of the flow in said inflow chamber.
 15. The downhole pulsing-shock reach extender method of claim 1, where said tapering constriction has a length substantially twice the diameter of said inflow chamber. 